Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), so the description is free to add value elsewhere — and it does, by disclosing the shape of the returned comparison (expected points, form, price, ownership side by side), which matters because there is no output schema. It does not mention limits or failure modes, so not a 5.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

A single front-loaded sentence that opens with the triggering condition ('Use this when...') and then supplies the concrete scenarios and output dimensions. No filler or redundancy.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

With no output schema, the description usefully summarizes what the comparison returns and frames the decision contexts. It is complete enough to invoke correctly, though it could say more about the horizon's effect on results or how ties/ranking are presented.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so the schema already documents both 'names' and 'horizon' (including the 1-8 range). The description only loosely echoes this with 'two or three players' and 'coming gameweeks'; the baseline of 3 is appropriate, and the 2-3 phrasing is slightly narrower than the schema's maxItems of 10.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb+resource ('compare FPL players') and enumerates exactly what is compared (expected points over coming gameweeks, form, price, ownership). This clearly separates it from siblings like get_player or find_players, which return single-player or search results.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description gives concrete selection scenarios ('Saka or Palmer?', one transfer for another, whether a -4 hit is worth it), so the agent knows when to reach for it. It stops short of naming an alternative tool or an explicit when-not condition, so it doesn't reach the 5 bar.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.